The invention pertains to auxiliary means for maintaining refrigerators at cooling temperatures utilizing ambient air.
Refrigerators, walk-in coolers, refrigerator display cases, and similar apparatus used in the preservation of food utilize refrigeration circuits operated by electrically driven compressors. As the power requirement for most commercial refrigeration devices is more than one horsepower, the energy utilized annually is significant, even though it is only desired to cool the controlled space to 40.degree. F. or the like.
In the northern climates the atmospheric temperatures are often 40.degree. F. or less during significant portions of the year, and yet, conventional refrigeration apparatus used in such climates, even during the coldest days, employs the usual compressor driven refrigeration circuit to maintain the desired cooling temperature.
Cool atmospheric temperatures have been utilized for food refrigeration purposes for many years, but in the past fifty years, the economical availability of electrical energy, and the close temperature control achievable in a cooled space with conventional refrigeration equipment under automatic control, has not encouraged the use of atmospheric air for refrigeration purposes. In view of the present need for energy conservation and due to increased energy costs, operators of large refrigeration equipment are interested in reducing their operating expenses, yet apparatus of a practical nature which would permit cool atmospheric air to be employed for refrigeration purposes has not heretofore been available.
The use of atmospheric air to cool refrigerated spaces has been long practiced, a typical installation being shown in U.S. Pat. No. 1,693,200, and it is also known to draw atmospheric air into a refrigerated space by the utilization of a fan as shown in U.S. Pat. No. 1,600,522. Also, in the air conditioning of buildings atmospheric air is often mixed with refrigerated air in the control of temperature and humidity, as typfied in U.S. Pat. Nos. 2,407,036 and 3,659,432. However, none of the known prior art can be readily utilized with refrigeration apparatus for achieving fully automatic operation, which is concise in construction, dependable in operation, and does not require modification to the existing compressor-operated refrigeration apparatus.